Electric engineering talks about parallel and series. (including the old parallel and serial ports on computers, before almost everything became serial)

Programming talks about parallelism or concurrency or threading. (single-threading, multi-threading)

Or synchronous and asynchronous.

The legal system talks about concurrent and consecutive.

Process descriptions might use "sequential" rather than consecutive or series.

"Linear" is another possibility, but it's overloaded since it's often used in reference to mathematics.